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At least 343 records · Page 19Linked to original sources
PubMed1984

Modifications of the structures of the rat lymph nodes by neonatal thymectomy.

Until recently, the deep cortex of the lymph node was thought to exist as a layer completely underlying the peripheral cortex. It was known, moreover, that through neonatal thymectomy, the lymphocyte population of the deep cortex could be depleted. Through our current research, however, we have demonstrated that the deep cortex actually consists of hemispherical 'units'. Each unit is centered under an opening of an afferent lymphatic and comprises a center and a periphery with different morphological features and functions. In the light of this new knowledge, we felt it appropriate to reexamine the influence of neonatal thymectomy on node histology. Rats were thymectomized 5 h after birth. When they were 8 weeks old, nodes from various anatomical sites were submitted for morphological analysis. The resulting observations were compared to those made with nodes of nude as well as normal rats. It was found that the histological changes induced by neonatal thymectomy were comparable to those resulting from the congenital athymic state, but with marked differences. Differences were also observed in the nodes of thymectomized and semi-thymectomized rats. The discussion deals with these differences and presents new observations.

Animals↗
PubMed1978

[Changes in adrenocortical activity in grown rats following thymectomy].

The authors measured arterial blood pressure by direct and indirect method in 80 adult rats and examined: content of ascorbic acid and cholesterol and the activity of alkaline and acid phosphatase in adrenals after thymectomy. The indices were followed in dynamics on the 15, 30, 45, 60 and 90th day after thymectomy. The established changes, manifested by a reduced concentration of the ascorbic acid and cholesterol in the early period of the experiment and the increased phosphatase activity during the whole period were interpreted as a manifestation of elevated adrenal activity after thymectomy. Activation of the adrenal cortex preceded the hypertensive reaction.

Acid Phosphatase↗
PubMed1983

Immunomodulation of murine B16 melanoma metastasis: thymosin, thymectomy and irradiation.

Thymosin, a product of the endocrine system, was used to further define the effects of immunomodulation of metastasis. Adult thymectomized C57BL/6 mice, 4 wk post-irradiation (400 R) had a decrease in the number of pulmonary metastasis (compared to controls) following tail vein injection of 5 X 10(4) B16 melanoma cells. Thymosin fraction 5 (fr. 5) administration (200 micrograms/mouse, 3 times weekly beginning 2 days post-thymectomy) returned the number of metastasis to the nonthymectomized values. Thymosin treatment of sham-operated, sham-operated irradiated, or thymectomized nonirradiated mice did not significantly elevate the number of metastases compared to the respective controls. Variant tumors which have an increase in metastasis following thymectomy and irradiation were also used. Thymosin administration reversed the effects of thymectomy in such variants, resulting in a decrease in metastasis. Metastases in thymosin-treated control mice were not significantly altered. A role for the thymus in metastasis via an endocrine product (thymosin) is suggested by these studies. Since thymosin did not increase metastasis in intact mice with tumors, further clinical trials with thymosin in cancer patients are not counterindicated by our results. These experiments confirm that thymosin fr. 5 is an important probe of the immunoendocrine events involved in tumor growth and metastasis.

Animals↗
PubMedDate not supplied

Evolution of the indications and results of treatment of myasthenia by thymectomy.

Four-hundred and fifty thymectomies from myasthenia were carried out at the Marie Lannelongue Surgical Center up to October 1980. This report deals with 248 patients who were operated on up to October 1977 and who were followed up for periods of 18 months to over 20 years with a view to examining the indications and results of thymectomy. In our opinion patients with thymomas should be operated upon when their general and cardiorespiratory condition allows surgery, and if there is no tumoral spread which precludes eradication. In the latter cases, irradiation and antimitotics are the only remaining resources. In 82% of the 248 patients who had a long term follow-up, results were good. In the group of patients obliged to continue regular medical treatment, thymectomy prevents deterioration, allows the patient to be administered better medical treatment, and to return to normal activity. Moreover, by reducing the risk of a tumor developing (75% of the cases), complementary irradiation treatment is avoided.

Female↗
PubMed1995

[Myasthenia gravis and 93 thymectomies. Therapeutic strategies and results 1990-1994].

The authors evaluate 93 thymectomies they performed in the course of five years. Indication for surgery was in all instances myasthenia gravis. Surgery was used only after conservative treatment, the patients had to be asymptomatic or have only minimal myasthenic manifestations. Thymectomy was associated with a 6.4% morbidity and zero mortality. On long-term follow-up the results were excellent or very good in 66.7% of patients and marked improvement was recorded in 30.1%. Thymectomy is part of comprehensive treatment of patients with myasthenia gravis.

Adolescent↗
PubMed1993

[Evaluation of results following thymectomy in myasthenia gravis].

Sixty-nine patients with generalized myasthenia gravis underwent thymectomy consecutively between 1980 and 1991 and were evaluated 1 month to 120 months after operation. Extended thymectomy was performed in 43 patients and other procedures in 26. The effect of thymectomy were as follows: 14.5% of the patients achieved complete remission (no symptoms, no medication), 73.9% showed improvement; in total 88.4% had palliation. The long-term changes of the remission rate at one and five years after operation were 11.5% and 19.2%, and showed a delayed remission. The long-term changes of the improvement and palliation rate were 55.7% and 67.2% at one year, 69.2% and 88.5% at five years after operation. There was significant difference in remission rate according to age at the time of operation and age of onset, but the response did not depend on sex, presence or absence of thymoma, preoperative duration of illness, Osserman's type and operative procedure.

Adolescent↗
PubMed1995

[Early thymectomy in the treatment of myasthenia gravis].

Over a 10-year period, 1983 through 1992, in the clinic of endocrinologic surgery--Alexander Hospital, Sofia, 89 patients with myasthenia gravis (MG), 57 women and 32 men, are subjected to operative treatment--thymectomy. The mean age in women is 32 years (range 19 to 68), and in men--45.6 years (range 25 to 70). Two age-related distributions in the series are impressive--in female patients the peak is between 20 and 30 years, whereas in men--between 45 and 55 years. The operative intervention consists in total thymectomy. Preference is given to the trans-sternal median access to the thymus gland. In the complex therapeutic approach to MG are included also a number of drugs and other agents--corticosteroids, anticholinesterase agents, immunosuppressives and the like. Patients undergoing operative thymectomy are usually given preoperative treatment with anticholinesterase drugs for different periods of time. Operation is undertaken only in stable condition of the patients. Good postoperative results are recorded in 57 per cent of those operated by the first year, with a satisfactory improvement in 29.2 per cent of them. In the third group (13.4 per cent) the postoperative results are poor, and treatment is proceeded with anticholinesterase drugs or immunosuppressives. The average follow-up term is 44.7 months. The delay in improvement is typical of patients with longer duration of the complaints, but it may be attained within 2, 3 or 5 years postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1996

[Thymectomy in myasthenia gravis].

Thymectomy is in most cases the treatment of choice in myasthenia gravis (MG). In order to evaluate the Danish results, we investigated the outcome and patient satisfaction following thymectomy in Odense University Hospital from 1980 to 1994. Thirty-three patients were operated. Five (16%) were completely without symptoms or medication and 14 (44%) received less medication and had fewer symptoms than preoperatively. Sex, age, degree of illness, duration of symptoms, histology of the thymus and surgical approach had no significant (p > 0.05) influence on the result. Four patients died 2-29 months after surgery, three because of aggravation of MG and one of causes unrelated to the operation. Of the 29 patients still alive none had serious complications, 11 had minor complications and 23 were satisfied with the operation. Thymectomy is recommended for patients with symptomatic MG, but the effect of surgery should be evaluated in a prospective clinically controlled study.

Adult↗
PubMed1996

Pathogenesis of post-thymectomy autoimmune gastritis. Identification of anti-H/K adenosine triphosphatase-reactive T cells.

Autoimmune gastritis spontaneously develops following thymectomy of 3-day-old BALB/c mice (d3Tx). These mice develop autoantibodies to the gastric parietal cell proton pump, H/K ATPase, and aberrant expression of the H/K ATPase in the neonatal thymus prevents the induction of disease post-thymectomy. To characterize the effector cells mediating autoimmune gastritis, we isolated H/K ATPase-enriched preparations of parietal cell microsomes and further purified the enzyme by lectin affinity chromatography. Both preparations induced significant proliferative responses of gastric lymph node cells, which were mediated by CD4+, MHC class II-restricted T cells. Surprisingly, T cells reactive to the Ag could only be demonstrated in lymph nodes in the immediate proximity of the stomach; little or no response was seen when mesenteric or peripheral lymph nodes were tested. It is likely that the H/K ATPase-reactive T cells are actually the effector cells in this disease, as they could only be detected in mice that developed gastritis, as indicated by anti-parietal cell Ab, gastric inflammation, and the presence of cells capable of transferring disease into nu/nu mice. H/K ATPase-specific T cell proliferative responses could first be detected 5 wk post-thymectomy and were accompanied by high background responses at this time point. These latter responses may represent enhanced syngeneic MLRs, which we have previously shown to be elevated in d3Tx mice. Characterizations of the H/K ATPase-reactive and self-reactive T cell populations may reveal the factors that break peripheral T cell tolerance and lead to the development of organ-specific autoimmune disease.

Animals↗
PubMedDate not supplied

Detection and morphology of thymic remnants after video-assisted thoracoscopic extended thymectomy (VATET) in patients with myasthenia gravis.

Thymectomy is often an extremely useful therapeutic procedure in myasthenia gravis (MG) and is usually indicated for adult patients with generalized disease. Because remnants of thymus may remain in extrathymic fat, an extended thymectomy is recommended. A new surgical approach without sternotomy: video-assisted thoracoscopic extended thymectomy (VATET) was performed in 30 MG patients. The weight of removed thymus ranged from 10.8 to 113 grams. The weight of fatty tissue removed from pretracheal, anterior mediastinal and costophrenic areas ranged from 6.3 to 74.8 grams. Histological examination revealed thymic remnants in 14.8% of pretracheal fat samples and in 33.3% of samples from anterior mediastinal plus costophrenic areas. These findings indicate that VATET is a radical procedure and may be the first choice surgery for young female MG patients, since aesthetic sequelae are reduced compared to procedures involving sternotomy.

Adipose Tissue↗
PubMed1997

[Thymectomy in myasthenia gravis].

Myasthenia gravis is a relatively uncommon autoimmune disorder of neuromuscular transmission. Surgical therapy plays an important role in addition to medical treatment. Follow-up results of 52 patients with thymectomy are presented. Between 1984-1996 thymectomy via median sternotomy was performed in 52 patients with myasthenia gravis (female = 28, male = 24). The score described by Ossermann and Genkins was used for classification. According to this classification, we found 12 patients in class II(I), 21 in class IIA, 17 in class IIB and 2 in class III, respectively. A thymoma was found in 19, follicular lymphoid hyperplasia in 24 and an atrophic thymus in 9 cases, respectively. There was no mortality. Severe postoperative complications consisted of bleeding and reoperation in one patient and another patient developed a sternal instability with consecutive operative refixation. Follow-up evaluation after a mean period of 36 months (min. 6 months, max. 130 months) revealed a relief of myasthenic symptoms in 37 patients. Thymectomy is effective in the treatment of myasthenia gravis with a low complication rate.

Adult↗
PubMed1988

Thymectomy in the treatment of myasthenia gravis: report of 247 patients.

We made a retrospective assessment of the long-term outcome in 247 consecutive patients with myasthenia gravis (MG) who underwent thymectomy in the period January 1971-December 1985. In 84 cases a thymoma was found at surgery, while 163 patients had a non-neoplastic thymus. The duration of symptoms before surgery, the age at onset of the disease and the presence of germinal centres in the thymus did not appear to influence the prognosis. Patients with a non-neoplastic thymus showed a better response to thymectomy. Thymoma was associated with more severe disease and with a higher mortality; moreover, more thymoma patients required corticosteroid treatment in order to achieve good therapeutic results. In our opinion, thymectomy is indicated in the treatment of generalized MG, while ocular myasthenia seems not to be improved by the removal of the thymus.

Adolescent↗
PubMed1976

Effects of thymectomy and antithymocyte serum on spontaneous regression of Friend virus-induced erythroleukemia.

To evaluate the role of immune response in regression of leukemia, we studied the effect of immunosuppression on the spontaneous regression of a leukemia induced by a specific strain of Friend murine leukemia virus complex (RFV). Thymectomy of newborn but not adult outbred Swiss mice markedly inhibited regression. The effect of antithymocyte serum (ATS) on regression depended on the timing of ATS treatment. Regression was markedly inhibited in leukemic mice given ATS just before the start of regression. During leukemia development, ATS treatment but not thymectomy potentiated splenomegaly and delayed the start of regression. Both ATS treatment and neonatal thymectomy increased mortality as a function of the decrease in disease regression. Treatment with normal rabbit serum also inhibited regression but, when given during leukemia development, affected neither the splenomegalic response to RFV nor the number of deaths. The data demonstrated that an intact immune system was required for leukemia regression and suggested that some thymus-dependent parameter of immune response was a major factor in regression.

Animals↗
PubMed1980

The influence of salivary glands extirpation and (or) thymectomy on some physiological and immunological parameters in rats.

Spleen weight, blood counts and anti-SRBC response were estimated in rats subjected to thymectomy and (or) salivary gland extirpation. A significant decrease of spleen weight and number of circulating lymphocytes was observed after thymectomy or salivary glands extirpation. The number of PFC after immunization with SRBC was decreased after thymectomy but not after salivary glands extirpation or, surprisingly, after combined surgery.

Animals↗
PubMed1982

Thymectomy in late-onset myasthenia gravis.

Between 1977 and 1979, 12 consecutive patients with myasthenia gravis who were over the age of 55 years were treated by thymectomy. In all, their conditions improved clinically; 11 of the 12 became free of the generalized features of myasthenia gravis. Nine patients required no further medication. Acetylcholine-receptor antibody titers did not change significantly. Although five patients had atrophic thymus glands, their conditions also improved. We conclude that (1) thymectomy is a safe and effective therapy for patients with myasthenia gravis who are over the age of 55 years; (2) steroids and anticholinesterase agents are not essential in the management of late-onset myasthenia gravis; and (3) reduction in acetylcholine-receptor antibody titer is not essential for beneficial clinical response.

Aged↗
PubMed1984

Myasthenia gravis in monozygotic twins. Clinical follow-up nine years after thymectomy.

Genetically proved monozygotic female twins in whom myasthenia gravis developed in their 20s initially had their disease well controlled with anticholinesterase medication. Because of increasing resistance to medication, twin 1 had her thymus removed, after which the symptoms decreased. Predicated on the improvement in her sister and the need for increasing medication to allay symptoms, and after proof of monozygosity, twin 2 also underwent thymectomy, with subsequent symptomatic improvement. The twins were followed up nine and six years after thymectomy, respectively. Monozygotic twins with myasthenia gravis are generally young women, with onset of disease in one occurring within one to three years of the other. Reports of only one affected twin may be misleading because of inadequate documentation of monozygosity, absence of long-term observation, or both. Serial investigations of the "uninvolved" twin in a monozygous pair and proof of monozygosity should be obtained to aid in early diagnosis and treatment of this illness, as well as to study the pathogenesis of myasthenia gravis prior to symptom onset.

Adult↗
PubMed1976

Transcervical thymectomy: an integral part of neck exploration for hyperparathyroidism.

Thirty-two neck explorations for hyperparathyroidism were done in 18 months. The indication for transcervical thymectomy was a failure to locate either inferior gland. Six of eight patients had adenomatous or hyperplastic glands located within or adjacent to the thymus. One infrathymic lesion was a parathyroid carcinoma and the other was a functioning parathyroid cyst. The abnormal parathyroid gland was not visible in any of these six patients until the thymus had been removed. Had this step been omitted, a sternotomy would probably have been required. Two patients had bilateral normal parathyroid glands within or deep to the thymus. Unless some normal parathyroid tissue has been identified and preserved, the indiscriminate use of transcervical thymectomy could result in the inadvertent excision of both inferior glands and possible iatrogenic hypoparathyroidism.

Humans↗
PubMed1997

Effects of thymectomy and tolerance induction on tumor immunity in adult Xenopus laevis.

Major-histocompatibility-complex homozygous partially inbred adults of the ff strain of Xenopus reject transplants of tumor cells of ff strain origin; ff tadpoles do not. Thymectomy, performed 5 days after fertilization, abrogated the adult tumor-rejection response suggesting that in this system tumor rejection is immunologically mediated by T cells. Thymectomy later in larval life did not alter tumor rejection, but it did reduce T-cell numbers. Tolerance to minor-histocompatibility(H) antigens segregating within the ff family, which was induced by grafting adult skin to metamorphosing larvae, did not affect the tumor-rejection capacity of the tolerant adult hosts. This suggests that the ff-2 tumor expresses (a) tumor-specific antigen(s). Immunization of larvae with tumor cells did not induce tolerance to skin grafts transplanted during adult life. Indeed, such grafts were rejected in accelerated fashion, suggesting that memory cells generated in the larvae persist through metamorphosis.

Animals↗